This project identifies and characterizes biochemical mechanisms for dopamine receptors. An understanding of the biochemical phenomena contributing to the activity of dopamine receptors will identify possible mechanisms of action for drugs used to treat Parkinson's disease, endocrine disorders, and psychiatric disorders. Among the topics studied in the current fiscal year are: investigation of the site of action of guanyl nucleotides in regulating beta-adrenergic stimulation and dopaminergic inhibition of adenylate cyclase activity in the intermediate lobe of the rat pituitary gland; 2) identification of specific D-2 receptor agonists, 3) demonstration that the D-1 receptor stimulates and D-2 receptor inhibits cAMP formation in the neostriatum.